[PATCH 6/6] slub: Allocate frozen pages

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

Since slub does not use the page refcount, it can allocate and
free frozen pages, saving one atomic operation per free.
---
 mm/slub.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index e5535020e0fd..420a56746a01 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1789,21 +1789,21 @@ static void *setup_object(struct kmem_cache *s, void *object)
 static inline struct slab *alloc_slab_page(gfp_t flags, int node,
 		struct kmem_cache_order_objects oo)
 {
-	struct folio *folio;
+	struct page *page;
 	struct slab *slab;
 	unsigned int order = oo_order(oo);
 
 	if (node == NUMA_NO_NODE)
-		folio = (struct folio *)alloc_pages(flags, order);
+		page = alloc_frozen_pages(flags, order);
 	else
-		folio = (struct folio *)__alloc_pages_node(node, flags, order);
+		page = __alloc_frozen_pages(flags, order, node, NULL);
 
-	if (!folio)
+	if (!page)
 		return NULL;
 
-	slab = folio_slab(folio);
-	__folio_set_slab(folio);
-	if (page_is_pfmemalloc(folio_page(folio, 0)))
+	slab = (struct slab *)page;
+	__SetPageSlab(page);
+	if (page_is_pfmemalloc(page))
 		slab_set_pfmemalloc(slab);
 
 	return slab;
@@ -2005,8 +2005,8 @@ static struct slab *new_slab(struct kmem_cache *s, gfp_t flags, int node)
 
 static void __free_slab(struct kmem_cache *s, struct slab *slab)
 {
-	struct folio *folio = slab_folio(slab);
-	int order = folio_order(folio);
+	struct page *page = (struct page *)slab;
+	int order = compound_order(page);
 	int pages = 1 << order;
 
 	if (kmem_cache_debug_flags(s, SLAB_CONSISTENCY_CHECKS)) {
@@ -2018,12 +2018,12 @@ static void __free_slab(struct kmem_cache *s, struct slab *slab)
 	}
 
 	__slab_clear_pfmemalloc(slab);
-	__folio_clear_slab(folio);
-	folio->mapping = NULL;
+	__ClearPageSlab(page);
+	page->mapping = NULL;
 	if (current->reclaim_state)
 		current->reclaim_state->reclaimed_slab += pages;
 	unaccount_slab(slab, order, s);
-	__free_pages(folio_page(folio, 0), order);
+	free_frozen_pages(page, order);
 }
 
 static void rcu_free_slab(struct rcu_head *h)
@@ -3541,7 +3541,7 @@ static inline void free_large_kmalloc(struct folio *folio, void *object)
 		pr_warn_once("object pointer: 0x%p\n", object);
 
 	kfree_hook(object);
-	mod_lruvec_page_state(folio_page(folio, 0), NR_SLAB_UNRECLAIMABLE_B,
+	lruvec_stat_mod_folio(folio, NR_SLAB_UNRECLAIMABLE_B,
 			      -(PAGE_SIZE << order));
 	__free_pages(folio_page(folio, 0), order);
 }
-- 
2.34.1